Messages in this thread | | | Subject | Re: [PATCH] kasan: Always respect CONFIG_KASAN_STACK | From | Alex Ghiti <> | Date | Thu, 14 Oct 2021 20:31:00 +0200 |
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Hi Nathan,
Le 14/10/2021 à 18:55, Nathan Chancellor a écrit : > On Fri, Oct 08, 2021 at 11:46:55AM -0700, Palmer Dabbelt wrote: >> On Thu, 23 Sep 2021 07:59:46 PDT (-0700), nathan@kernel.org wrote: >>> On Thu, Sep 23, 2021 at 12:07:17PM +0200, Marco Elver wrote: >>>> On Wed, 22 Sept 2021 at 22:55, Nathan Chancellor <nathan@kernel.org> wrote: >>>>> Currently, the asan-stack parameter is only passed along if >>>>> CFLAGS_KASAN_SHADOW is not empty, which requires KASAN_SHADOW_OFFSET to >>>>> be defined in Kconfig so that the value can be checked. In RISC-V's >>>>> case, KASAN_SHADOW_OFFSET is not defined in Kconfig, which means that >>>>> asan-stack does not get disabled with clang even when CONFIG_KASAN_STACK >>>>> is disabled, resulting in large stack warnings with allmodconfig: >>>>> >>>>> drivers/video/fbdev/omap2/omapfb/displays/panel-lgphilips-lb035q02.c:117:12: >>>>> error: stack frame size (14400) exceeds limit (2048) in function >>>>> 'lb035q02_connect' [-Werror,-Wframe-larger-than] >>>>> static int lb035q02_connect(struct omap_dss_device *dssdev) >>>>> ^ >>>>> 1 error generated. >>>>> >>>>> Ensure that the value of CONFIG_KASAN_STACK is always passed along to >>>>> the compiler so that these warnings do not happen when >>>>> CONFIG_KASAN_STACK is disabled. >>>>> >>>>> Link: https://github.com/ClangBuiltLinux/linux/issues/1453 >>>>> References: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier") >>>>> Signed-off-by: Nathan Chancellor <nathan@kernel.org> >>>> >>>> Reviewed-by: Marco Elver <elver@google.com> >>> >>> Thanks! >>> >>>> [ Which tree are you planning to take it through? ] >>> >>> Gah, I was intending for it to go through -mm, then I cc'd neither >>> Andrew nor linux-mm... :/ Andrew, do you want me to resend or can you >>> grab it from LKML? >> >> Acked-by: Palmer Dabbelt <palmerdabbelt@google.com> >> >> (assuming you still want it through somewhere else) > > Thanks, it is now in mainline as commit 19532869feb9 ("kasan: always > respect CONFIG_KASAN_STACK"). > >>>> Note, arch/riscv/include/asm/kasan.h mentions KASAN_SHADOW_OFFSET in >>>> comment (copied from arm64). Did RISC-V just forget to copy over the >>>> Kconfig option? >>> >>> I do see it defined in that file as well but you are right that they did >>> not copy the Kconfig logic, even though it was present in the tree when >>> RISC-V KASAN was implemented. Perhaps they should so that they get >>> access to the other flags in the "else" branch? >> >> Ya, looks like we just screwed this up. I'm seeing some warnings like >> >> cc1: warning: ‘-fsanitize=kernel-address’ with stack protection is not supported without ‘-fasan-shadow-offset=’ for this target > > Hmmm, I thought I did a GCC build with this change but I must not have > :/ > >> which is how I ended up here, I'm assuming that's what you're talking about >> here? LMK if you were planning on sending along a fix or if you want me to >> go figure it out. > > I took a look at moving the logic into Kconfig like arm64 before sending > this change and I did not really understand it well enough to do so. I > think it would be best if you were able to do that so that nothing gets > messed up. >
I'll do it tomorrow, I'm the last one who touched kasan on riscv :)
Thanks,
Alex
> Cheers, > Nathan > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv >
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